Abstract:The study and applications of fluorescent proteins has gone a long way from a subject of highly specialized research to a widely known and indispensable tool for in vivo labeling, and from a single known member⎯Green Fluorescent Protein from Aequorea victoria⎯to hundreds of natural proteins of different colors with still poorly studied phylogeny and biological significance.

My talk will be focused on fluorescent proteins with “unusual” spectral or biochemical characteristics. In particular, we developed KillerRed – phototoxic fluorescent proteins capable of light-induced production of reactive oxygen species (ROS). KillerRed allows lightinduced ROS production to be strictly localized to different compartments and subcompartments within a cell. It was shown that KillerRed-mediated oxidative stress at different locations results in clearly different molecular events and cell responses (e.g., triggering apoptosis for mitochondria-localized KillerRed, or DNA damage and temporal blockage of cell division for chromatinlocalized KillerRed).

Recently, we designed CFP variant with an anionic tryptophanbased chromophore. In contrast to green and red fluorescent proteins usually containing anionic tyrosine-based chromophores, no charged states of the CFP chromophore have been described before. We believe that switching between protonated and deprotonated tryptophan in chromophores of fluorescent proteins represents a new unexplored strategy to control their spectral properties.